In the conventional methods for producing a thermoplastic resin film, a thermoplastic resin film melt-extruded from a die is brought into contact with a cooling drum, to be quickly cooled to lower than the glass transition temperature of the resin, for forming a cast film low in crystallinity, good in clarity and smooth on the surface. It is, as required, in succession stretched monoaxially or biaxially.
However, these methods have the following problem.
The maximum speed at which a film low in crystallinity, good in clarity and smooth on the surface can be obtained by bringing a molten thermoplastic resin film into contact with a cooling drum is about 40.about.60 m/min at the highest, since it cannot be prevented that the air is caught in the clearance between the cast film and the cooling drum irrespective of whether any casting means effective for high speed casting such as electrostatic charging, vacuum suction or pressing is used. So, the productivity is inevitably low.